Drip irrigation nozzle

ABSTRACT

A drip irrigation nozzle having pressure regulating and selfcleaning characteristics. The nozzle includes a resilient closure member which in a flow limiting position partially blocks the nozzle metering orifice in proportion to the pressure of the supplied fluid. The nozzle discharge or &#39;&#39;&#39;&#39;drip&#39;&#39;&#39;&#39; rate thus is substantially independent of fluid supply pressure. When the irrigation fluid is turned on or off, the transient burst of fluid past the closure member cleans debris from the nozzle.

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McMahan States Patent [1 1 DRIP IRRIGATION NOZZLE [75] Inventor: Walter C. McMahan, Escondido,

Calif.

[52] US. Cl. ..239/454, 239/541 239/542 [51] Int. Cl. ..B05b l/30 [58] Field of Search ..239/542, 547, 550, 454, 456,

[56] References Cited UNITED STATES PATENTS 1,481,470 1/1924 LaLonde 137/202 812,451 2/1906 Rice ..137/202 2,075,589 3/1937 Munz ....239/204 X 340,226 4/1886 Lindsley ..137/202 492,597 2/1893 Way ..137/202 1,576,331 3/1926 Kelley et a1 ..137/202 March 6, 1973 1,845,618 2/1932 Miller ..239/454 1,880,880 10/1932 Dietsch..... ...239/206 X 1,899,711 2/1933 Munz ..239/204 FOREIGN PATENTS OR APPLICATIONS 334,929 6/1919 Germany ..239/452 Primary Examiner-M. Henson Wood, Jr.

Assistant Examiner-John J. Love Attorney-Flam & Flam [57] ABSTRACT past the closure member cleans debris from the nozzle.

19 Claims, 10 Drawing Figures PATENTEUHAR SL975 3119,32?

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BY Warm/j 3 fl-rroeJevs PATENIED 6075 3.719327 sum 2UF 2 l v h l INVENTOR. I

52 E 3% BY 5! 1 I A 3 7 IQTTOQAJE vs DRIP IRRIGATION NOZZLE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to drip irrigation systems, and particularly to fluid nozzles, emitters or droppers for such systems.

2. Description of the Prior Art Extensive research has determined that the productivity of plants is increased vastly if the root zone is not subjected to extremes in wetting and drying. Thus the objective of a drip irrigation system is to provide regulated moisture content for the soil surrounding the plant roots. Such an irrigation system typically consists of l) a control center cooperable with a water supply and including filters, control valves, pressure gauges and apparatus for dissolving fertilizer into the irrigation water; (2) water distribution pipes of suitable size, including laterals and T-connects; and (3) nozzles, emitters or droppers attached to the T-connects. Preferably, the nozzles include metering orifices which discharge irrigation water at a rate of less thanabout two gallons per hour.

Several problems are associated with prior art drip irrigation systems. First, due to the small size of the metering orifices, the nozzles tend to become clogged by the accumulation of dirt, residue, or impurities from the water supply. Such blockage is unacceptable, since no water will be provided to the root zone irrigated by that nozzle. Efforts to prevent orifice blockage have related to improving the filters used at the control center. Such filters are costly to install, require periodic maintenance, and are of limited effectiveness. An object of the present invention is to provide a drip irrigation nozzle which is self-cleaning, thereby permitting some laxity in filtering system performance.

Another problem associated with drip irrigation systems relates to the pressure drop along a particular lateral. It is common practice to connect 30, 40 or even more droppers or nozzles to a single lateral. While the pressure drop between successive nozzles may be small, the pressure drop between the nozzle nearest the control center and those at the end of the lateral is substantial. Also there can be a significant difference in relative height of emitters due to hilly terrain; the resultant variation in water pressure along the lateral will cause substantially different amounts of water to be emitted at different stations. Another object of the present invention is to provide a nozzle structure having an automatically adjusting orifice which compensates for such pressure differences, and which has a manual adjusting feature to control the emitter drip rate.

Still another prior art problem relates to nozzles wherein the metering orifice remains open even when the fluid supply is turned off. Various types of insects like to spin webs in the small nozzle holes. Such webs then tend to impede the flow of irrigation water through the nozzle. Another object of he present invention is to provide a drip irrigation nozzle in which the orifice is maintained closed when not in use. While in operation this device ejects a small stream of water that is readily visable from a distance thus making routine checking simple. Should the emitter become plugged, a tap of the foot on the plunger will clear it.

0 eliminating the need for standby portable sprinklers.

SUMMARY OF THE INVENTION To accomplish the foregoing objects, there is provided a simple drip irrigation nozzle having self-cleaning and pressure regulating characteristics. The nozzle includes a resilient closure member which assumes a flow limiting position partially blocking the metering orifice by an amount directly proportional to the pressure of the supplied fluid. Accordingly, the higher the irrigation water pressure, the smaller the effective orifice. A regulating function thus is achieved.

The nozzle is purged of accumulated deposits when the fluid supply is turned on and off. This cleaning function is accomplished by the transient high volume fluid flow through the nozzle which remain substantially open during the transient period as the closure member moves into or away from the flow limiting position. When the fluid supply is off, the flanged top of the shaft supporting the closure member covers the nozzle outlet to keep out insects.

BRIEF DESCRIPTION OF THE DRAWINGS A detailed description of the invention will be made with reference to the accompanying drawings. These drawings, unless described as diagrammatic or unless otherwise indicated, are to scale.

FIG. 1 is a simplified, diagrammatic view of a drip irrigation system.

FIG. 2 is a perspective view of a drip irrigation nozzle in accordance with the present invention, partly broken away to show the closure member.

FIG. 3 is a transverse sectional view of the nozzle of FIG. 2, as viewed generally along the line 33 thereof; the nozzle is shown in the quiescent state.

FIG. 4 is a transverse sectional view in the same aspect as FIG. 3, but with the closure member shown in the flow limiting position.

FIG. 5 is a bottom sectional view of the nozzle shown of FIG. 3, as viewed generally along the line 5-5 thereof.

FIG. 6 is a transverse sectional view, and FIG. 6A is a plan view, partly in section, of another nozzle embodiment similar to that of FIG. 2, with a flow metering notch provided on the closure member.

FIG. 7 is a perspective view of another drip irrigation nozzle in accordance with the present invention.

FIG. 8 is a transverse sectional view of the nozzle of FIG. 7, as viewed generally along the line 88 thereof.

FIG. 9 is a bottom sectional view of the nozzle of FIG. 7, as seen generally along the line 99 thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following detailed description is of the best presently contemplated modes of carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention best is defined by the appended claims.

Structural and operational characteristics attributed to forms of the invention at first described also shall be attributed to forms later described, unless such characteristics obviously are inapplicable, or unless specific exception is made.

Referring now to the drawings and particularly to FIG. 1 thereof, there is shown diagrammatically a drip irrigation system for maintaining regulated moisture content of the soil 11 in the root zone of plants under cultivation. The irrigation system 10 includes a control center 12 at which water from a supply is connected via appropriate control valves and pressure gauges (not shown) to a distribution network including a lateral 13. Fertilizer may be mixed with the irrigation water at the control center 12.

The lateral 13 typically is underground, and provided with a plurality of T-connects 14 each of which conducts the supplied irrigation water upward above ground level to a drip irrigation nozzle 15 of the type disclosed herein. Each nozzle 15 functions to dispense the irrigation fluid at a slow but constant rate, independent of the fluid pressure present at the particular T- connect 14 associated with that nozzle; Uniform, regulated soil moisture content is achieved.

A first embodiment of the invention is shown in FIGS. 2 through 5. Referring thereto, the drip irrigation nozzle 15A includes a generally cylindrical outer body member 16 which may be exteriorly threaded to facilitate attachment to the upper end 14a of a T-connect 14. With such arrangement, the chamber 17 within the outer body member 16 is in fluid communication with the supply conduit or lateral 13.

The upper end 16a of the member 16 is closed except for a central, interiorly threaded opening 16b. A generally cylindrical inner body member 18 screws into the opening 16, and includes an axial opening 180 which functions as the fluid outlet path for the nozzle 15A. The member 18 has a hex-headed end 18b.

Situated within the chamber 17 is a closure member 21, preferably fabricated of a resilient plastic or rubber material and having a diameter slightly greater than the diameter of the opening 16b. Supporting the closure member 21 is a shaft 22 extending through, and having a diameter somewhat less than the opening 18a. The upper end of the shaft 22 includes a flange 22a which limits the downward travel of the shaft 22 and. the closure member 21, and which serves as a cover for the opening 18a when the nozzle 15A is in the quiescent state illustrated in FIG. 3. For simplicity, the shaft 22 may comprise a wood screw, the head of which forms the flange 220.

One or more notches 24 are cut in the underside 160 of the outer body member end 16a. Each notch 24 may have a generally triangular shape as viewed in transverse section (FIG. 3 or 4), and extends radially outwardly from the opening 16b, as shown in FIG. 5. As described below, the notches 24 serve as the metering orifices for the nozzle 15a.

When fluid is supplied through the lateral 13, the water pressure within the T-connect l4 and the chamber 17 forces the closure member 21 upward against the lower surface 16c of the outer body member end 16a. In this flow limiting position (FIG. 4), the closure member 21 substantially blocks off fluid flow between the chamber 17 and the annular space 23 surrounding the shaft 22 within the opening 18a. However, the diameter of the closure member 21 is less than the maximum radial extend of the notches 24. As a result, a fluid flow path remains from the chamber 17 through the exposed portion 24a of each notch 24 to the annular space 23 and thence out from the top end 18b of the inner body member 18. The size of the metering orifice 24a determines in part the fluid flow or drip" rate from the nozzle 15A.

As noted earlier, the closure member 21 is resilient. Accordingly, this closure member 21 will extrude into the notches 24 to a greater or lesser degree depending on the pressure of the fluid supplied via the T-connect 14. If the pressure is high, as at the source end of the lateral 13, the closure member 21 will extrude to a greater degree into each notch 24, and a smaller orifice 24a will result, Conversely, near the terminal end of the lateral 13 the pressure will be lower, and the member 21 will extrude to a lesser degree into notches 24. The openings 24a will be larger. In either case (high pressure and a small opening 24a or low pressure and a larger opening 24a), the resultant fluid flow rate through the annular discharge passageway 23 and out of the nozzle 15A will be substantially the same. Thus a pressure regulating function is achieved.

The drip rate of the nozzle 15A may be adjusted by changing the relative position of the inner body member 18 within the opening 16b. Thus if the member 18 is screwed in sufficiently far, the lower end of the inner body member 18 will partially eclipse the notch 24, thereby reducing the effective size of the orifice 24a. The net flow rate thereby is reduced. This adjustment function is described more thoroughly in conjunction with the embodiment of FIGS. 7 to 9.

When the irrigation fluid in the lateral l3 first is turned on, there will be transient period as the closure member is carried upward from the quiescent position of FIG. 3 to the flow limiting position of FIG. 4. During this transient period the supplied fluid will flow relatively freely through the space 25 (FIG. 3) above the upper end of the closure member 21 and out through the discharge passageway 23. The resultant pulse of fluid will flush out any residue which may have accumulated within the nozzle 15A. When the closure member 21 reaches the flow limiting position, the transient burst of water will terminate.

Later, when the supply of water to the lateral 13 is turned off, there will occur another transient period. As the water pressure decreases, the closure member 21 will drop away from the flow limiting position of FIG. 4, and another burst of water will flow through the space 25 and the passageway 23 again to flush out the nozzle 15A.

As an optional feature, a disc shaped filter screen 26 may be attached coaxially to the lower end of the closure member 21, as shown in phantom in FIG. 3. The screen 26 may include peripheral grooves 26a or small holes 2611 through which water but not debris can flow. When the closure member 21 is in the flow limiting position shown in FIG. 4, the periphery of the screen 26 will be in relatively close contact with the inner surface of the body member 16, so that all of the water supplied via the T-connect 14 will be filtered by the screen 26.

Another modification of the invention is shown in FIGS. 6 and 6A. Therein, the nozzle 15A is configured like the nozzle 15A of FIG. 2, however the inner body member 16' is not notched. Rather, a notch 27 is provided in the upper surface 21a of the resilient closure member 21' supported by the shaft 22'. Further, the inner body member 18' is of sufficient length so that the lower end 18c thereof projects beneath the inner body member surface 16c.

The pressure the irrigation fluid supplied via a T-connect 14 forces the closure member 21 into the flow limiting position shown in FIG. 6. In this condition, a limited amount of fluid flows from the chamber 17' through the notch 27 to the discharge passageway 23'. The cross-sectional dimension of the notch or metering orifice 27 establishes the drip rate. When considerable fluid pressure is present, the closure member 21' will be compressed against the inner body surface 18c, effectively reducing the size of the metering orifice 27. Conversely, with a lower fluid supply pressure the closure member 21' will not be compressed as much, and the effective dimension of the metering orifice 27 will be greater. Thus the drip rate will be substantially independent of the fluid supply pressure; a regulating function again is achieved.

Although not specifically illustrated, the notched closure member 21' (FIG. 6) may be employed together with a notch outer body member 16 (FIGS. 3 to 5). The notches 24 and closure member notch 27 then may cooperate as metering orifices.

Another embodiment of the invention is shown in FIGS. 7, 8 and 9. Therein, a drip irrigation nozzle 158 includes a generally cylindrical outer body member 31 exteriorly threaded for attachment to a coupling 32 connected to the upper end of a T-connect 14. The outer body member 31 may be fabricated of metal and include a hex head 31a to facilitate insertion into the coupling 32. The threaded interior opening 31b is of uniform diameter throughout the entire length of the outer body member 31. A pair of slots or notches 31c are provided at the lower end 31d of the outer body member 31. The notches 310 are of generally rectangular cross-section and extend radially from the opening 31b to the exterior surface of the outer body member 31.

An inner body member 33, like the inner body member 18 described above, is threadingly received within the opening 31b. The length of the inner body member 33 is sufficient so as to eclipse more or less the notches 310. The extend to which the inner body member 33 eclipses or covers the slots 31c establishes the drip rate from the nozzle 158.

The nozzle 158 also includes a resilient closure member 34 supported at a lower end of a shaft 35 which extends through the inner body member 33 to define an annular discharge passageway 36. The elements 34, 35 and 36 correspond respectively to the closure member 21, the shaft 22 and the passageway 23 in the embodiment of FIG. 2.

Preferably, the diameter of the closure member 34 is greater than the diameter of the opening 31b, and may 6 equal the external diameter of the outer body member 31. Thus, the pressure of the irrigation fluid in the T- connect 14 will force the closure member 34 against the outer body member over end 31d, as shown in phantom in FIG. 8. In this flow limiting position, fluid can drip through the uneclipsed portion 37 of the notched 31c, thence out through the discharge passageway 36.

A relatively high fluid supply fluid will cause the resilient closure member 34 to extrude partway into the notches 31c, reducing the effective size of the metering orifice 37. Conversely, a lower fluid pressure will result in less extrusion of the closure member 34, and hence in a larger effective size of the metering orifice 37. Again, the pressure regulating function is achieved.

As described above in conjunction with the nozzle 15A, a transient burst of water also will flow past the closure member 34 to cleanse the discharge passageway 36 as the fluid supplied via the lateral 13 is turned on an off. Note that when the supply fluid is on, the shaft upper end 35a may be depressed by hand or foot to permit unimpeded fluid flow past the closure member 34 and out through the passageway 36. The resultant rush of water will further cleanse the nozzle 15B. Moreover, the flanged end 35a of the shaft 35 functions as a lid or cover to close the discharge passageway 36 when the nozzle 15B is in the quiescent condition. This prevents insects from entering and spinning webs within the passageway 36.

The nozzle 1513 may be used as a full circle sprinkler by unscrewing the inner body member 33 (FIG. 8) sufflciently far as to expose completely the slotted orifices or notches 310. The substantial quantity of water flowing through the uneclipsed notches 310 will be discharged via the passageway 36 and deflected into a full circle spray by the inclined undersurface of the shaft end 35a.

Thus there is provided a novel drip irrigation nozzle having both self-cleaning and pressure regulating characteristics, which can be flushed out by depressing the exposed shaft end, and which can be converted easily to a full circle sprinkler.

Intending to claim all novel, useful and unobvious features shown or described, the applicant:

I claim:

1. A drip irrigation nozzle comprising:

a generally cylindrical outer body member adapted for connection to a fluid supplying conduit,

a generally cylindrical inner body member threadedly mounted within said outer body member to permit adjustment of the relative axial position of said inner and outer body members,

a resilient closure member,

a closure supporting shaft extending through said inner body member with a fluid flow permitting discharge passageway therebetween, said closure member being attached to said shaft, fluid supplied via said conduit forcing said closure member toward a fluid flow limiting position against said inner or outer body member, and

a metering orifice allowing fluid to drip past said closure member and through said discharge passageway when said closure member is in said fluid flow limiting position, said resilient closure member more or less closing said metering orifice in response to variation in fluid supply pressure, thereby providing a substantially uniform fluid drip rate independent of fluid supply pressure.

2. A drip irrigation nozzle according to claim 1 wherein said outer body member has a conduit connecting portion forming a housing for said closure member, one end of said housing being closed except for an interiorly threaded opening therethrough.

3. A drip irrigation nozzle according to claim 2 wherein the diameter of said closure member is greater than the interior diameter of said interiorly threaded opening, said housing one end being notched to form said metering orifice.

4. A drip irrigation nozzle according to claim 2 further comprising a filter disc disposed transversely across the interior of said housing and attached to the lower end of said closure member.

5. A drip irrigation nozzle according to claim 2 wherein a surface of said closure member is notched, and wherein said inner body member projects beyond said housing one end, said notched closure member surface seating against said inner body member in said fluid flow limiting position.

6. A drip irrigation nozzle according to claim 1 wherein said metering orifice comprises at least one notch in the surface of said closure member which is forced against said body member in said fluid flow limiting position.

7. A drip irrigation nozzle according to claim 1 wherein the end of said outer body member facing said conduit is notched radially, said relative axial position establishing the degree to which said inner body member eclipses said notch to control the amount of fluid dripping therethrough when said closure member is in said flow limiting position against said notched end.

8. A drip irrigation nozzle according to claim 1 wherein the other end of said shaft includes a flange abutting against said inner body member to limit the extent of travel of said closure member away from said flow limiting position and to cover the discharge passageway through said inner body member when no fluid is supplied by said conduit.

9. A drip irrigation nozzle according to claim 8 wherein said shaft is disposed vertically, said closure member dropping downward away from said flow limiting position when said fluid supply is terminated, said closure member being forced upwardly toward said flow limiting position by the pressure of said fluid when said supply is turned on, said nozzle being cleaned by the burst of fluid flowing past said closure member during the transient period taken for said closure member to reach or drop away from said flow limiting position.

10. A drip irrigation nozzle according to claim 1 wherein said metering orifice comprises at least one notch in the end of said inner body member facing said closure.

11. A drip irrigation nozzle according to claim 1 wherein said metering orifice comprises at least one notch in the surface of said outer body member facing said closure.

12. For use in a drip irrigation system wherein irrigation fluid is supplied via a conduit to a plurality of nozzles, a nozzle including:

a. a first body member having associated means for connection to said conduit and having a discharge passageway therethrough,

b. a resilient closure member fabricated of rubber or plastic,

c. said closure member being attached to a shaft loosely extending through said discharge passageway, the other end of said shaft cooperating with said first body member to permit limited travel of said closure member toward or away from said first body member,

(1. a metering orifice in the fluid path from said con duit to said passageway,

e. fluid from said conduit forcing said closure member toward a position in which fluid flow between said conduit and said passageway is limited only to said metering orifice, the extent to which said closure member blocks said orifice being proportional to the supplied fluid pressure, thereby providing a uniform drip rate substantially independent of pressure variation along the conduit.

13. A nozzle according to claim 12 wherein said metering orifice comprises a notch in the end of said closure member facing said first body member.

14. A nozzle according to claim 10 adapted to be flushed clean by depression of said other shaft end to move said closure member away from said flow limiting position, thereby permitting water to rush through said discharge passageway.

15. A nozzle according to claim 12 wherein said first body member is adjustably positioned within a second body member adapted for connection to said conduit.

16. A nozzle according to claim 15 wherein said metering orifice comprises a notch in said second body member.

17. A nozzle according to claim 16 wherein said first body member may be adjustably positioned to eclipse a portion of said notch to establish said drip rate.

18. A nozzle according to claim 15, said nozzle being convertible into a full circle sprinkler by adjustably positioning said first body member not to eclipse said metering orifice, said shaft having a conical upper end, fluid flowing through said discharge passageway being deflected into a circular spray by said shaft conical upper end.

19. A drip irrigation nozzle comprising:

a generally cylindrical outer body member adapted for connection to a fluid supplying conduit,

a generally cylindrical inner body member adapted for mating engagement within said outer body member,

a resilient'closure member,

a closure supporting shaft extending through said inner body member with a fluid flow permitting discharge passageway therebetween, said closure member being attached to said shaft, fluid supplied via said conduit forcing said closure member toward a fluid flow limiting position against said inner or outer body member, the other end of said shaft including a flange abutting against said inner body member to limit the extent of travel of said closure member away from said flow limiting position and to cover said discharge passageway when no fluid is supplied by said conduit, said shaft comprising a screw, and

a notched metering orifice allowing fluid to drip past said closure member and through said discharge passageway when said closure member is in said fluid flow limiting position, said resilient closure 

1. A drip irrigation nozzle comprising: a generally cylindrical outer body member adapted for connection to a fluid supplying conduit, a generally cylindrical inner body member threadedly mounted within said outer body member to permit adjustment of the relative axial position of said inner and outer body members, a resilient closure member, a closure supporting shaft extending through said inner body member with a fluid flow permitting discharge passageway therebetween, said closure member being attached to said shaft, fluid supplied via said conduit forcing said closure member toward a fluid flow limiting position against said inner or outer body member, and a metering orifice allowing fluid to drip past said closure member and through said discharge passageway when said closure member is in said fluid flow limiting position, said resilient closure member more or less closing said metering orifice in response to variation in fluid supply pressure, thereby providing a substantially uniform fluid drip rate independent of fluid supply pressure.
 1. A drip irrigation nozzle comprising: a generally cylindrical outer body member adapted for connection to a fluid supplying conduit, a generally cylindrical inner body member threadedly mounted within said outer body member to permit adjustment of the relative axial position of said inner and outer body members, a resilient closure member, a closure supporting shaft extending through said inner body member with a fluid flow permitting discharge passageway therebetween, said closure member being attached to said shaft, fluid supplied via said conduit forcing said closure member toward a fluid flow limiting position against said inner or outer body member, and a metering orifice allowing fluid to drip past said closure member and through said discharge passageway when said closure member is in said fluid flow limiting position, said resilient closure member more or less closing said metering orifice in response to variation in fluid supply pressure, thereby providing a substantially uniform fluid drip rate independent of fluid supply pressure.
 2. A drip irrigation nozzle according to claim 1 wherein said outer body member has a conduit connecting portion forming a housing for said closure member, one end of said housing being closed except for an interiorly threaded opening therethrough.
 3. A drip irrigation nozzle according to claim 2 wherein the diameter of said closure member is greater than the interior diameter of said interiorly threaded opening, said housing one end being notched to form said metering orifice.
 4. A drip irrigation nozzle according to claim 2 further comprising a filter disc disposed transversely across the interior of said housing and attached to the lower end of said closure member.
 5. A drip irrigation nozzle according to claim 2 wherein a surface of said closure member is notched, and wherein said inner body member projects beyond said housing one end, said notched closure member surface seating against said inner body member in said fluid flow limiting position.
 6. A drip irrigation nozzle according to claim 1 wherein said metering orifice comprises at least one notch in the surface of said closure member which is forced against said body member in said fluid flow limiting position.
 7. A drip irrigation nozzle according to claim 1 wherein the end of said outer body member facing said conduit is notched radially, said relative axial position establishing the degree to which said inner body member eclipses said notch to control the amount of fluid dripping therethrough when said closure member is in said flow limiting position against said notched end.
 8. A drip irrigation nozzle according to claim 1 wherein the other end of said shaft includes a flange abutting against said inner body member to limit the extent of travel of said closure member away from said flow limiting position and to cover the discharge passageway through said inner body member when no fluid is supplied by said conduit.
 9. A drip irrigation nozzle according to claim 8 wherein said shaft is disposed vertically, said closure member dropping downward away from said flow limiting position when said fluid supply is terminated, said closure member being forced upwardly toward said flow limiting position by the pressure of said fluid when said supply is turned on, said nozzle being cleaned by the burst of fluid flowing past said closure member during the transient period taken for said closure member to reach or drop away from said flow limiting position.
 10. A drip irrigation nozzle according to claim 1 wherein said metering orifice comprises at least one notch in the end of said inner body member facing said closure.
 11. A drip irrigation nozzle according to claim 1 wherein said metering orifice comprises at least one notch in the surface of said outer body member facing said closure.
 12. For use in a drip irrigation system wherein irrigation fluid is supplied via a conduit to a plurality of nozzles, a nozzle including: a. a first body member having associated means for connection to said conduit and having a discharge passageway therethrough, b. a resilient closure member fabricated of rubber or plastic, c. said closure member being attached to a shaft loosely extending through said discharge passageway, the other end of said shaft cooperating with said first body member to permit limited travel of said closure member toward or away from said first body member, d. a metering orifice in the fluid path from said conduit to said passageway, e. fluid from said conduit forcing said closure member toward a position in which fluid flow between said conduit and said passageway is limited only to said metering orifice, the extent to which said closure member blocks said orifice being proportional to the supplied fluid pressure, thereby providing a uniform drip rate substantially independent of pressure variation along the conduit.
 13. A nozzle according to claim 12 wherein said metering orifice comprises a notch in the end of said closure member facing said first body member.
 14. A nozzle according to claim 10 adapted to be flushed clean by depression of said other shaft end to move said closure member away from said flow limiting position, thereby permitting water to rush through said discharge passageway.
 15. A nozzle according to claim 12 wherein said first body member is adjustably positioned within a second body member adapted for connection to said conduit.
 16. A nozzle according to claim 15 wherein said metering orifice comprises a notch in said second body member.
 17. A nozzle according to claim 16 wherein said first body member may be adjustably positioned to eclipse a portion of said notch to establish said drip rate.
 18. A nozzle according to claim 15, said nozzle being convertible into a full circle sprinkler by adjustably positioning said first body member not to eclipse said metering orifice, said shaft having a conical upper end, fluid flowing through said discharge passageway being deflected into a circular spray by said shaft conical upper end. 